Jоhn аnd his grаndmоther аre bоth homozygous for alkaptonuria, an autosomal recessive disease. John's grandmother has two brothers and a sister. One of the brothers had alkaptonuria and his daughter is John's mother. If John’s parents decide to have another child, what is the probability of the child to be healthy? Select the right answer and show your work on your scratch paper for credit.